fix(node): one member holds a share of the node, sized past real use

128 peer sessions on the node, at most 64 per account (the hub names the
account with each offer; the node's own account is not counted). One account
plays at most half the stream slots, rounded up, and runs two subtitle
extractions at once. Frames after the handshake are 8 MiB (was 64), decoded
with per-container bounds, and a frame refused for either ends the session
instead of jamming its buffer (F-16).

Sized for the heaviest real member: twenty groups on one node, three devices
and a tab, up to 52 sessions. Measured: ~0.15 MiB and one fd per idle session.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 11 insertions, 4 deletions

diff --git a/packages/meshbay-node/src/meshbay_node/transport/webrtc/apps/subtitles.py b/packages/meshbay-node/src/meshbay_node/transport/webrtc/apps/subtitles.py
index 70781eb..35211af 100644
--- a/packages/meshbay-node/src/meshbay_node/transport/webrtc/apps/subtitles.py
+++ b/packages/meshbay-node/src/meshbay_node/transport/webrtc/apps/subtitles.py
@@ -10,6 +10,7 @@ from meshbay_common.protocol import MNP
 
 from meshbay_node.media_probe import probe_video as _probe_video
 from meshbay_node.roots import off_disk
+from meshbay_node.transport.webrtc.apps.streaming import MAX_SUBTITLE_JOBS_PER_ACCOUNT
 from meshbay_node.transport.webrtc.disk import _locate
 from meshbay_node.transport.webrtc.media_tools import (
     _extract_subtitle_to_webvtt,
@@ -135,10 +136,16 @@ class SubtitlesMixin:
                 return
 
             budget = _subtitle_timeout_for(entry.size)
-            async with sem:
-                log.info("subtitle: extracting file=%s track=%d (slot taken, up to %.0fs)",
-                         file_id[:12], ordinal, budget)
-                blob = await _extract_subtitle_to_webvtt(file_path, ordinal, budget)
+            with self._account_share("subtitles", MAX_SUBTITLE_JOBS_PER_ACCOUNT) as ok:
+                if not ok:
+                    log.info("subtitle: refused, account at its extraction share")
+                    self._send({"type": "error",
+                                "detail": "Subtitles are already being prepared, retry shortly"})
+                    return
+                async with sem:
+                    log.info("subtitle: extracting file=%s track=%d (slot taken, up to %.0fs)",
+                             file_id[:12], ordinal, budget)
+                    blob = await _extract_subtitle_to_webvtt(file_path, ordinal, budget)
 
             subtitle_hash = blake3.blake3(blob).hexdigest()
             await media_cache.put_thumb(subtitle_hash, synthetic_id, blob)